Horn or amplifier



S. RASMUSSEN July 28,1931.

HORN OR AIPLIFIER I s Shegts-She't 1 Filed April 5,

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July 28, 1931. s. RASMUSSEN 1,316,545

HORN OR AIPLIFIER Filed April 5, 1930 3 Sheets-Sheet 2 32 9. 3 gig. 4

dttmg Patented July 28, 1931 STATE-5 ,SVERBE a musse 9 NEW r se I-IORN OB AMPLIFIER Application filed April 5, 1930. Serial No. 441L920.

This invention relates to amplifiers, and more particularly to an amplifying horn used uponfplionographs, radios and the like.'

Amplifying horns now in usehave been found unsatisfactory, as they only consist of, aj'sing-le chamber or cone and high notes require a shorter and smaller cone for their properamplification. Itis therefore one object'of. this'inventiOn to :provide an amplifier consisting of eithera cone or chamber and a plurality of chambers 'of'smaller dimensions distributed about walls of the main chamber, or a number of chambers of various dimensions so that high, low andintermediate tones may be properly reproduced and muffiing and distorting eliminated.

Another object of the invention is to permit the small amplifying chambers to be either formed directly into the walls or head at the outer end ofthe main horn ,or body, or formed as separate units and applied to the walls of the main horn either internally or extern ally thereof.

Another object'vof the invention is to provide device of this character which is very simple in its construction and not liable to get out of order. i I i i The invention is illustrated in the accompanying drawings, wherein:

Fig. 1 is a viewshowing a horn formed in accordance with this invention and disclosed partly in elevation and partly in section.

Fig, Zis a front eleyation of the hornshown in Fig. 1. 'i i 'Fig. 3 is a View in front elevation illustrating a slightly modified form of horn.

Fig. 4 is a front elevation of another di cation. te m of ern- Fig. 5 is front elevation of a further modified construction.

Fig. .6 is a diagrammatic view of a form of the invention in which the small or auxiliary chambers are formed separately from the main; horn and secured thereinabout its walls.

Fig. 7 is a fragmentary diagrammatic view showlng the auxlliary horns or chambers applied lnternally and externally of the main horn. i

Fig. 8 is a diagrammatic view similar to Fig. 10 is a sectional View taken on the line 10,10 of Fig. 8.

Fig. 11 is a longitudinal sectional view showing the auxiliary chamberof Fig. 10 detached. from the main horn.

12 is a longitudinal sectional View taken on the line 1212 of Fig. 6.

"Fig. 18 is a longitudinal sectional View through the auxiliary chamber shown in Fig. 12.

I This improved amplifying device consists of a main horn or chamberl and a plurality M .n of smaller aux l ary chambers d stributed about the walls of the main chamber, or it mayconsist of a hollow substantially conical body having a plurality of chambers of vari ous'sizes formed in a head or its outer or forward end, as shown in Fig. 5.

Referring to Figs. 1 and 2, it will be seen that the main horn gradually increases in diameter from its rear or inner end towards its forward or outer end. Thishorn may have a spiral portion 2 or may extond substantially straight throughout its length, and also may be formed for a portion of its length with a plurality of passages which merge into each other in spaced relation to its ends. This hornmay be formed of balsa wood, or a suitable substitute throughout its length. It may also 'be formed of fibre for a portion of its length and have its forward portion formed of balsa wood, or if desired, may have its smaller or rear end formed of metal, its intermediate portion of fibre, and its forward portion of balsa wood. If the horn is formed entirely or partially of balsa wood, this portion will have its inner surface coated with ambroid, or an equivalent substance, in order to impart a small, glass-like surface.

As the walls of the horn approach the outer or forward end, they gradually increase in thicknes as clearly shown in Fig. 1. Therefore, although the conical chamber defined by these walls increases in diameter towards the outer or forward end of the horn, vibrations will be prevented and distortion eliminated.

t should be further noted that from the point indicated by the numeral 3, the inner surfaces of the walls are curved, as shown at 1, so that the chamber is abruptly enlarged to form an annular pocket in which the sound receives an impetus, and this annular pocket terminates in a circinnferentially extending shoulder 5, which borders the inner end of a large mouth or open central portion 6 of the horn. The walls of the horn about this open mouth are quite thick as shown in Fig. 2, and these walls are bored to form the auxiliary chambers or horns 7 which taper inwardly as clearly shown in Fig. 1, and are then flared slightly, and at their inner ends opened through the shoulder 5. By this arrangement the sound waves will pass through the small chambers or horns 7 as well as through the large mouth 6, the overtones being amplified in the small chambers 7 and thus restored to their natural strength in proportion to the fundamental.

From an inspection of Fig. 2 it will be seen that the small auxiliary horns or chambers may be of various dimensions instead of all the same size. Therefore certain sound which would not be properly amplified in chambers of a certain dimension will be properly taken care of in other auxiliary chambers, and these tones, when they finally pass to the outer atmosphere, through the main mouth 6 and auxiliary chambers will produce a very natural reproduction.

Instead of having the main horn substantially circular in front elevation, as shown in 2, it may be of the shape shown in F 3, wherein the main horn is indicated by the numeral 8, and has the main'chamber 9 formed in its lower portion and the auxiliary chambers located above the main chamber, as shown at 10, or the horn may be formed as shown in Fig. 4, wherein the horn indicated by the numeral 11, has a flat under-face 12, and is provided with a main chamber 13 and auxiliary chambers 14 disposed. above and at opposite sides of the main chamber. This form of reproducer could be embodied in a radio speaker of the table type. In Fig. 5 there has been shown a further modification wherein the horn is of substantially the same construction as shown in Fig. 1, but has its forward or outer end formed with a head 15 bored to form a large number of chambers 16 corresponding in shape to the small chambers 7, but distributed throughout the area of the head. These chambers 16 preferably consist of a number of relatively large chambers formed in the central portion of the head and surrounded by smaller chambers which decrease in diameter towards the margins of the head, but it is to be understood that any arrangement of chambers desired may be adopted.

In Fig. 6, there has been shown a diagrammatic View of another embodiment of the invent-ion. This is also illustrated in Fig. 12, and one of the auxiliary horns or chambers used in this form of the invention has been shown separately in Fig. 13. In this embodiment of the invention, the main horn 17 is 3 formed of thin wood which may be treated with the ambroid. This horn is quite similar in construction to those now in use upon phonographs and other sound-reproducer instruments, and in order to provide the auxiliary chambers, I employ a number of small auxiliary horns 18 which may be of various sizes, as clearly shown in Fig. 6. These auxiliary horns are preferably formed of balsa wood, and are bored to form chambers 19, which in contour conform to the chambers 7. The auxiliary chambers 18 are disposed with in the main horn and may be firmly secured in proper spaced relation to each other about its walls in any desired manner.

In Fig. 7 there has been illustrated in diagram, a fragmentof another modified form of amplifier. Referring to this Figure, and to Figure 9, it will be seen that a main horn 20 corresponding to the horn 17 has been used, and small auxiliary horns 21, which correspond to the horns or chambers 18 but are preferably all of the same dimensions, are secured against the inner surfaces of the walls of the main horn, and other auxiliary horns or chambers 22 are secured against the outer surfaces of the walls of the horn. These auxiliary horns 22 are of various diameters as clearly shown in Fig. 7, and each is bored to form a chamber corresponding substantially in shape to the chambers 7 and 19. The auxiliary horns 22 are of slightly greater length than the horns 21, and have their inner or rear ends firmly secured in openings 23, formed through the walls of the main horn, immediately to the rear of the inner ends of the horns 21. It will thus be seen that sound waves moving outwardly will be divided and portions thereof will pass through the inner auxiliary horns, while other portions will pass through the outer auxiliary horns.

The form of the invention disclosed in Fig. 8 is quite similar to that shown in Fig. 7, except that the inner auxiliary horns have been omitted, and only outer auxiliary horns indicated by the numeral 24 are applied to the walls of the main horn 25.

Referring more particularly to Figs. 10 and 11, where the form of invention shown in Fig. 8 is also illustrated, it will be seen that the auxiliary horns are of the same construction disclosed in Fig. 9 and are applied to the main horn in the same manner with their inner ends secured in openings formed through the walls of the main horn. These auxiliary chambers are also quite similar to those shown in Figs. 12 and 13, except that their inner ends are extended to engage in the openings formed in the walls of the main horn, and it is to be understood that if so desired, they may be formed as shown in Figs. 12 and 13 and have their inner ends secured against the walls of the main horn in surrounding relation to openings formed therein.

The terms and expressions which I have employed are used as terms of description and not of limitation, and I have no intention, in the use of such terms and expressions, of excluding any equivalents of the features shown and described, or portions thereof, but recognize that Various modifications are possible within the scope of the invention claimed.

lVhat I claim is:

1. In an amplifier, a main amplifying chamber having an annular wall, and a plurality of auxiliary amplifying chambers distributed within the wall of the mainchamber.

2. In an amplifier, a main amplifying chamber having a wall increasing in thickness towards the front of the chamber, the said wall having auxiliary amplifying chambers formed within said wall, and at their inner ends opening into the main chamber in spaced relation to the forward end thereof.

3. In an amplifier, a main amplifying chamber having a wall increasing in thickness toward the front of the chamber, the said wall having auxiliary amplifying chambers formed entirely within, said wall leading from the forward marginal edge of the main chamber and tapered rearwardly and at their inner ends opening into the main chamber.

4. In an amplifier, a main amplifying chamber gradually increasing in diameter towards its front end and at its front end having its wall bored to form a plurality of auxiliary amplifying chambers tapered inwardly and at their inner ends opening into the main chamber.

5. In an amplifier, a main amplifying chamber gradually increasing in diameter towards its front end and in spaced relation to its front end abruptly increasing in diameter and being then reduced in diameter to form an open mouth having a. bordering shoulder about its inner end, the wall of the chamber about the mouth being bored to form auxiliary amplifying chambers leading inwardly from the front edge face of the wall and tapered inwardly with their inner ends opening through the shoulder into the main chamber.

6. In an amplifier, a main amplifying chamber gradually lncreaslng in diameter to- 'wards its front end and in spaced relation to SVERRE RASMUSSEN. 

